The present invention relates to a method for operating a motor vehicle having an internal combustion engine, in which the operation of the motor vehicle is influenced depending on at least one operating parameter determined during an operating time of the motor vehicle.
German Patent No. 28 00 433 describes determining the total distance traveled by the motor vehicle and/or the total operating time of the motor vehicle. In this method, a limit speed of the internal combustion engine is changed depending on the total distance traveled and/or the total operating time in such a way that during a breaking-in period, only a relatively low speed of the internal combustion engine is possible. Overrevving of the internal combustion engine during the breaking-in period is to be prevented in this way.
However, it is problematic in the known method that with it the motor vehicle can nonetheless not always be operated optimally. The present invention therefore has as its object the refinement of a method of the type initially cited so that the motor vehicle can be operated as optimally as possible over its entire service life.
This object is achieved in a method of the type initially cited in that an operating parameter suitable for determining wear and tear of the motor vehicle is detected, a value corresponding to the wear and tear is determined, and the operation of the motor vehicle is adjusted according to the value determined.
According to the present invention, wear and tear is understood as the deterioration of an initially optimum state of the motor vehicle or its components due to wear or other reasons. It is thus possible with the method according to the present invention to respond to wear and tear which is unavoidable in the course of the life of the motor vehicle and to take appropriate measures which allow operation of the motor vehicle corresponding to the state of wear and tear. In this way, on one hand, the service life of the motor vehicle and its components is lengthened and, on the other hand, for example, emission mileage, fuel consumption, and comfort during operation of the motor vehicle are improved.
Thus, it is suggested that with increasing wear and tear, bucking of a drive train is prevented and/or counteracted through an appropriate change of at least one control parameter of the internal combustion engine. Particularly in motor vehicles having rear wheel drive, in the course of the life of the motor vehicle, the drive train, especially the drive shaft, becomes softer around its circumference due to the repeated and/or constantly occurring torsional stresses. Through the detection of wear and tear according to the present invention, this type of softening of the drive train can be deduced and bucking caused by a soft drive train can be prevented and/or counteracted through appropriate measures, e.g., control interventions in the transmission or the internal combustion engine itself.
In an embodiment of the present invention, it is further suggested that a knock detection threshold of the internal combustion engine be set higher with increasing wear and tear. Thus, for example, a new internal combustion engine is quieter than an old, worn out internal combustion engine. This can be detected and the changed combustion behavior can be appropriately counteracted by an intervention, e.g., in the ignition point.
In another refinement of the method according to the present invention, the ignition angle of the internal combustion engine is delayed with increasing wear and tear. This measure is based on the knowledge that in older, worn out internal combustion engines, deposits are present which make optimum combustion of the fuel more difficult with an early ignition angle, which is favorable per se for other reasons. Among other things, this results in older internal combustion engines no longer having optimum emission mileage. This is countered by delaying the ignition angle of the internal combustion engine.
If necessary, a threshold, above which a diagnostic unit infers a fault of a part of the motor vehicle, can be set higher with increasing wear and tear. Through this measure, the fact is taken into account that in the course of the life of a motor vehicle, for example, specific parts have greater play, due to vibrations, without a malfunction or an expected malfunction of the part having to be inferred due to this play. On the other hand, this type of greater play would not be acceptable in a new vehicle. This is taken into consideration according to the present invention in that a corresponding diagnostic unit operates xe2x80x9cmore tolerantlyxe2x80x9d with increasing wear and tear.
It is also particularly preferred in the method according to the present invention if the amount of change of the operating parameter is detected. From this, additional information about the load of the motor vehicle can be obtained and conclusions can in turn be drawn from this about the wear and tear of the motor vehicle.
A further preferred refinement of the method according to the present invention is that the operating parameter is integrated. In this way, a value relevant for wear and tear over the service life of the motor vehicle is provided in a simple way.
Examples of these types of integrated operating parameters are the mileage of the motor vehicle, the number of crankshaft rotations and the number of drive shaft rotations of the internal combustion engine. These operating parameters can be obtained easily in all motor vehicles having an internal combustion engine.
Furthermore, it is possible that the integrated operating parameter is the operating temperature of the internal combustion engine, preferably integrated over the operating period and/or the number of crankshaft rotations and/or the mileage of the motor vehicle. In this way, it can, for example, be recognized whether the internal combustion engine is frequently operated in the unfavorable cold operating state, which allows inference of greater wear and tear and of a specific type of wear and tear.
Furthermore, the operating parameter can be an acceleration, preferably along the longitudinal axis of the vehicle. This allows, for example, conclusions about the wear and tear of the drive train to be drawn.
In the course of the service life of a motor vehicle, deposits occurring in the internal combustion engine, and particularly in the combustion chamber and/or in the intake passage, can preferably also be recognized directly by appropriate sensors or during an inspection. A corresponding operating parameter is then formed from this, on whose basis corresponding interventions then occur, e.g., in the course of engine management.
The present invention also relates to a computer program which is suitable for performing the previously described method when it is executed on a computer. It is particularly preferable in this case if the computer program is stored in a memory, particularly in a flash memory.
Finally, the present invention also relates to a control system for operating a motor vehicle having an internal combustion engine, having at least one sensor with which an operating parameter of the motor vehicle is determined and having a control unit which influences the operation of the motor vehicle depending on the operating parameter determined.
In order to be able to operate the motor vehicle optimally during its entire service life, it is suggested according to the present invention that the sensor detect an operating parameter suitable for determining wear and tear of the motor vehicle and the control unit determine a value corresponding to the wear and tear and adjust the operation of the internal combustion engine to the determined value. This type of control system has the advantage that, with it, the motor vehicle can be operated essentially optimally over its entire service life.